Draw any circle and mark
(a) its centre
(b) a radius
(c) a diameter
(d) a sector
(e) a segment
(f) a point in its interior
(g) a point in its exterior
(h) an arc
(a) O
(b) OP
(c) PQ
(d) POR
(e) ST
(f) O
(g) M
(h) PR